More block enhancements

[etoledom]

Fixes #859

As mentioned in #859 (comment), I opted for modifying the More block to be read only, in order for it to be ready for the next release.

More info and test steps on the gutenberg side PR: WordPress/gutenberg#16005

On the design side, I noticed on web that More block and Page Break block look the same, so I implemented the same design we use for Page Break on mobile too, but I'll wait for @iamthomasbishop 's input on this.

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[iamthomasbishop]

Nice work! A couple of little things I wanted to document – although not specific to the Read More block (also applies to the Page Break block):

• The divider should extend to the ends of the canvas/container
• The label should be sans-serif
• Ideally the divider should be a dashed line, but I think that might've been a compromise bc of CSS limitations in the RN app

[etoledom]

Thank you for the review @iamthomasbishop !

The divider should extend to the ends of the canvas/container

I was able to extend the lines a bit more, until the edge of the block content.

We can extend them more using some negative magic margin values, but I'm not sure if that's what you had in mind, and it might not be a very good idea :)

The label should be sans-serif

✅

Ideally the divider should be a dashed line, but I think that might've been a compromise bc of CSS limitations in the RN app

The lines are actually a normal (thin) view with a background color. Not possible to make them dashed with the current component we are using. I'd recommend this to be a future enhancement.

This is an updated screenshot:

[koke]

Not possible to make them dashed with the current component we are using. I'd recommend this to be a future enhancement

For reference, some initial effort going (on hold) here: WordPress/gutenberg#14175

[koke]

If @iamthomasbishop is good with the visuals, the implementation looks good to me

[iamthomasbishop]

Looks great to me! Thanks for the updates @etoledom!

[etoledom]

Thank you both!